Objective: Cervical ectopy is common in adolescents, during pregnancy and with oral contraceptive use (OC). Our first objective was to determine whether the areas of ectopy and the transformation (T) zone were greater in adolescents using combined estrogen-progestin OCs compared to a long-acting progestin contraceptive, depot medroxyprogesterone acetate (DMPA), and to identify other correlates of ectopy and the T zone. Our second objective was to examine whether a larger area of ectopy places adolescents at a greater risk of chlamydial infection. In addition, we evaluated the rate of HPV infection by cervical measurements and other indicators of cervical maturation. Our third objective was to evaluate the effects of estrogen and progesterone on the risk of chlamydial and HPV infection we compared adolescents using combined estrogen- progestin OC with those using a progestin only contraceptive, depot medroxyprogesterone acetate (DMPA).